Improvement in lifting-bridges



WITNESSES:

zsheetS--sheem S. SWABTZ. Lfing-Bridges.

Patented Feb. 25, 18.173.

WWINVENTOR:

ByW/ttorneys.

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S.v SWABTZ.

Lifting-Bridges.

PatentedlFeb. 25,1873.

NOQ 136,278.

INVENTOR:

'UNITED I STATES PATENT?? OEEICEn SAMUEL SVARTZ, OF BUFFALO, NEW YORK.

IMPROVEMENT IN LIFTINGIBRIDGES.

Specification t'orn'iing part of Letters Patent No. 136,278, datedFebruary 25, 1871.

To all whom 'it may concern:

Be it known that I, SAMUEL SWARTZ, of Bu'alo,fin the county ot' Erie,New York, have invented an Improved Liftin g-Brid ge, of which thefollowing is a specification:

Nat/ure and Objects of the Invention.

This invention, although applicable to drawbridges in general, is moreespecially designed for those used on canal-slips and like narrowwater-ways; and the invention comprises an improved plan forcounterbalancing and lift- Y ing the bridge proper. The inventionfurther comprises a means for supporting or securing the bridge in anydesired position.

The construction and arrangement of the bridge is primarily intended toobviate any obstruction to the tow-line as applied to canalslips.

Dcscriptfion of thc Drawing.

Securely xed in the bank of the canal, and on one side of the slip to bespanned, are two posts or stanchions, a little more distant from eachother than the width ofthe bridge proper. Ot' these stanchionsone,which, in the present illustration, is composed, in fact, ot' twosimilar posts, A A', is arranged on the inner side ofthe tow-path, andhas an altitude about equal to half the length ot' the bridge. Theheight of the other post, B, is just sufficient to aordjournal-bearingfor one end of a pivot-shaft, O, whose other end has journal-bearings inthe post A. To this shat't C is firmly attached the "heel7 end of asuitable trussbridge, preferably of the form represented at D.Projecting rectangularly or nearly rectan gularly downward from theshaft C are arms E E', from which struts F F' proceed directly to theunder side of and near the mid-length of the bridge, where they meet andcoact with truss-rods Gr G', which constitute members of the bridge. Theends of the struts F F' ,which pass through the arms E E', arescrew-threaded to receive nuts fj", by means of which the said strutsmay be shortened or lengthened, so as to bring said struts to theirproper strain and tautness, and to compensate for any torsional yieldingof the shaft, or for any sag of the bridge proper, so as to maintain theremote corner n of the "toe or free end ot the bridge at its properelevation relative-ly to the other parts ot' the bridge. This support ordistribution of the strain andlitting-pressure may be still furtheraided and secured by diagonal planking, as shown in Fig. 1. Projectingupward from the shaft C is a semicircular ratch et, H, all of whoseteeth h, save one or two, h', on the inner end, have their pointsdirected reverse] y to the ascending rotation of the bridge, so as toenable the retention of the bridge at any desired elevation, or inhorizontal position, by means of a catch-pawl, I, which has two claws, JJ', ot' which claws one claw, J, is capable of being engaged in theteeth h and the other claw of being engaged in one ofthe teeth h',according as the handle I is thrown outward or inward. When the saidhandle I is Ain the vertical position neither one of its claws isengaged, and the bridge is then at liberty to be either elevated ordepressed. The pivot-shaft G is also provided with a seg ment spur wheelor rack, K, in which gears a pinion, L. The shaft of this pinion isprovided with a crank, M, by means ot' which the bridge is raised andlowered. The posts A A' have pivoted between them, near their upperends, a balance-beam, N, whose length about equals that ot1 the bridgeproper, and whose inner end is connected, by a chain, cable, or rod, O,with a wrist, P, which projects from the bridge proper near itsmid-length and below its center of gravity. From the other end of thebeam'y N depends a chain, cable, or rod, Q, which is weighted with acounter-balance, lt.

Upcfratt'on.

yproaches the entirely-open position, at which stage the preponderatingportion of the bridge above the wrist, coming in aid of thecounterbalance, now operates to hold the bridge in the elevated or openposition, as shown in Fig. 2. y

lt will be seen that the struts F F', with their nuts ff', acting inconjunction With the truss-pieces G G', enable the lifting action on thewrist P at the middle of one side of the bridge proper to be transmittedequally to both sides of the bridge, and be effective at the end of thesame remote from the pivot-shaft. It will also be seen that the bridgemay be lifted and held as long as necessary at any height.

I am aware that a draw-bridge Working on a horizontal pivot andcounterbalanced to facilitate lift-ing it is not new; and this Idisclaim.

Claims.

.l claixn as new and of my i nventionl. The horizontal pivot-shaft Gwith arms EE@ the pivoted bridge D,ythe struts F F', the liftingmechanism K LM, and the balancevbeam N with the counter-Weight R,arranged,

G G', substantially as described.

3. The provision, on thepivot-shaft of a drawbridge, of the ratchet H hh', in the described combination with the catch-pawls I J J'.

SAMUEL SWARTZ.

YVitnesses:

BENJ. H. AUsTIN, Jr., ARTHUR W. HICKMAN.

